Life in an Arsenic-Containing Gold Mine: Genome and Physiology of the Autotrophic Arsenite-Oxidizing Bacterium Rhizobium sp. NT-26

Abstract

Arsenic is widespread in the environment and its presence is a result of natural or anthropogenic activities. Microbes have developed different mechanisms to deal with toxic compounds such as arsenic and this is to resist or metabolize the compound. Here, we present the first reference set of genomic, transcriptomic and proteomic data of an Alphaproteobacterium isolated from an arsenic-containing goldmine: Rhizobium sp. NT-26. Although phylogenetically related to the plant-associated bacteria, this organism has lost the major colonizing capabilities needed for symbiosis with legumes. In contrast, the genome of Rhizobium sp. NT-26 comprises a megaplasmid containing the various genes, which enable it to metabolize arsenite. Remarkably, although the genes required for arsenite oxidation and flagellar motility/biofilm formation are carried by the megaplasmid and the chromosome, respectively, a coordinate regulation of these two mechanisms was observed. Taken together, these processes illustrate the impact environmental pressure can have on the evolution of bacterial genomes, improving the fitness of bacterial strains by the acquisition of novel functions.

Transcriptomics analysis defines global cellular response ofAgrobacterium tumefaciens5A to arsenite exposure regulated through the histidine kinases PhoR and AioS

“…Previous microarray‐based As III exposure studies were conducted with Herminiimonas arsenicoxydans (Cleiss‐Arnold et al ., ) and Rhizobium NT‐26 (Andres et al ., ). The PSR has yet to be characterized in either organism, but we note that PSR culture conditions used in the current study were very similar to those described for the ‘Late Phase’ expression patterns of H. arsenicoxydans (Cleiss‐Arnold et al ., ).…”

“…The PSR has yet to be characterized in either organism, but we note that PSR culture conditions used in the current study were very similar to those described for the ‘Late Phase’ expression patterns of H. arsenicoxydans (Cleiss‐Arnold et al ., ). A PSR scenario is less clear for Rhizobium NT‐26 (Andres et al ., ) because of the relatively high starting Pi concentration in the media used (1.25 mM), although this is similar to that used for A. tumefaciens strain GW4 (Wang et al ., ; ) and thus potentially may have translated to a PSR condition in the stationary phase cells used by Andres and colleagues (). To clarify this situation, the PSR needs to be characterized in these organisms so as to determine if there are substantive variations among these bacteria.…”

Ecological speciation in bacteria: reverse ecology approaches reveal the adaptive part of bacterial cladogenesis

“…Sometimes however, genes with a nomadic past are domesticated by the core 298 genome and these associations can yield successful specialists, as exemplified by Salmonella as an obligatory pathogen 299 [75] or Rhizobium sp. NT-26 as a toxic mine resident [76]. 300…”

“…by conserving the flanking recombinogenic integrases or ISs), 352 allowing the genetic basis for the selected trait to evolve more dynamically. For instance, accumulation of functionally 353 related genes in an integron can build up the organism's fitness relative to a specific ecological aspect [76,88]. 354…”

Pseudorhizobium pelagicum gen. nov., sp. nov. isolated from a pelagic Mediterranean zone

“…More recently, Rhizobium sp. NT-26, isolated from a contaminated acid mine, was shown not to form nodules and lacked both nodulation and nitrogen fixation genes [3]. Nevertheless, as most genera of family Rhizobiaceae contain symbiotic and non-symbiotic species and it is possible that future species of the new genus Pseudorhizobium can be able to form nitrogen-fixing nodules in legumes, we have not included these characteristics in the genus or species descriptions.…”